It is also true that many people who want a tough looking “pitbull” are terrible owners who want their dog to attack and to be aggressive as a form of personal and home defense and raise them accordingly.
I didn't really know much about pits or have any opinion until one of my buddies adopted one and it killed his two cats with him trying to pry its mouth open. I started to look into the issue after that.
I have heard a good measure for physical strength required is that you should be able to carry any fully grown dog you own. If you can’t pick them up and carry them a short distance you probably do not have the physical stength to handle them.
Pets are like your children, you're responsible for keeping an eye on them always and to be accountable for what harm they cause to others, unless its truly a one-off case, which it almost never is in all the horrifying cases of dog to human attacks.
Speaking of overpowering, I used to walk a German Shepherd at a shelter many years ago. He wasn't well trained and in the beginning he used to tug at the leash with all his might. He was rather strong and not being dragged along was a good challenge for any adult human. This was despite the fact that he had only one hindleg. Eventually I taught him to walk without a leash. However, I will never forget him because he demonstrated to me how strong dogs are. It is not hard to exert control over them but if it has to be via physical means, it is not easy.
However, I should clarify, the point regarding being able to lift a dog that you own is not so that you can physically control the dog in a dominating fashion (I am of the opinion you should not try to dominate a dog as with a large or powerful dog it could end badly). It is more so that if you are walking the dog and it suddenly pulls towards a squirrel or something you are not instantly pulled off balance. Also, if the dog were to be injured that you could get the dog to your vehicle to drive to the vet.
Your point, however, is well taken. Police K-9s may only weigh 50 lbs but easily take full grown men weighing 200 lbs to the ground. No one should try to dominate a dog. That teaches them that that is how you interact with people and they will eventually do it to someone else if not you.
Some dogs do have a very high prey drive and may see small animals / children instinctively as prey. Typically this can be socialized out at puppyhood, but for some dogs it may require constant reinforcement. If it is not addressed at puppyhood it may always be an issue and the dog just won’t be suitable to have around babies and small pets.